A couple Newbie exhaust ???'s

[3000gt_vr4]

ok i have a completely stock 92 vr4 , and i had a few questions about the exhaust. only because i want to get a bit more sound out of it. i was thinking of just going down to a shop that i have done business with and getting a full 3 in pipe , but im not sure what i need to keep(cat, pre cats, or mufflers) or if i need to buy new cat. i know that a full 3" cat back will cost me 250-300 bucks. but what kinda confuses me is the big muffler on the driver side and the two smaller ones on the passenger side. do i get rid of it all and get two normal sized mufflers or would i have to get two diffrent sizes.

[Polygon]

You can dump the pre-cats. When you get your emissions done you will just have to make sure that your cat gets nice and hot first. You can replace the two with one cat as long as you get a good sized one. AS for the muffler one good sized one should take care of it.

[3000gt_vr4]

so are the two passenger side things are the little mufflers or are the cats.

[nawz8r]

That's some kind of resonating chambers on the passenger side, the muffler is on the drivers. That whole apparatus is called the cat back meaning: from the catalytic converter on back, I guess. So, the main cat is midway on the car, ahead of it is the downpipe, and before the dp are the precats - one for each side of the engine.

[3000gt_vr4]

oh ok so what would be best removing both pre cats or the single cat.

[linchpinjoe]

3.5" straight pipes or open precats.

Best sound evar.

[axispiral]

i had these same questions when i first starting thinking about doing exhaust, so I'm more than willing to help a fellow 3s'er out. ok

First, the things in red circles are the precats, they do the same thing as the main catalytic converter, but are mostly for when the car is starting from cold and the main cat is not heated up yet. Don't really need these, as Polygon stated earlier. Can gut them, like a lot of people on here do and still keep the pipe. the thing in the blue circle is the main catalytic converter, if you plan on passing emissions, keep this on, it is illegal to drive without one on you car. the whole part circled in the purple is what is going to be replaced if you buy an eBay downpipe. So make sure you know what youa re buying, and if its what you want. also, if you get a dp that replaces the main cat and front cat, all you have to do is gut the rear cat and you will have a VERY NICE SOUND. not too loud at idle and low rpms, but pretty mean at high revs. thats what I have right now and really like it. and in terms of HP gains, that is better than putting on a cat back. maybe later down the road if you are planning to make more power, you can up grade the whole system, but i've heard on here that the rest of the cat-back part of the exhaust doesn't restrict too much airflow untill you start making about 400hp crank (correct me if im wrong).

Now if you just want better sound, but not obnoxiously loud, the downpipe that replaces the main cat and front precat+gutting the rear precat would be good. and cheaper than a cat back system, but would make you car illegal, so you can do what you originally said and just get a cat back.

For the most part, it will not give you too much in the way of HP gains, but it will drastically change the sound of the car. The cat back is the part circled in the orange/brown color. That whole section of the exhaust system is located behind the catalytic converter and is thus called a cat-back (DUHH!!). This consists of some piping, the muffler/resonator, circled in green, and the exhaust tips. Now your car probably has active exhaust so that is what you see under the driver side of the car. The way exhaust works in our cars is that when in sport mode, the exhaust fumes come back into the main muffler, and it comes out of the two exhaust tips on the driver side as well as going through the pipe coming out of the main muffler and out to the tips on the passenger side as well. when in tour mode, it closes of the pipe going to the passenger side and makes the car quieter.

Now this is all cool to know, but if you're gonna change out the system, that all doesn't matter, just have the shop you go to fab a 1 to 2 split system, when the one pipe that comes back from the main cat splits into two pipes and you can put two separate mufflers on each of those. Thats seems to be what a lot of people on here do, put the mufflers right where the exhaust tips currently are. like this guy did

or if you are looking at performance and weight loss rather than just sound, you can look into a single shot exhaust, which basically just continues the single pipe coming back from the main cat, bends a few times and then has a muffler on it when it comes out the back of the car. This is "better" because it is less metal, which means less weight, and is an easier path for the air to escape out the back of the car, for example:


both will give you a lot more sound, but IMO the dual tip system just looks better, mostly because our cars came with duals and there are two spots on our bumpers.

Basically, there are a few things you can do to get more sound, as you said you wanted. you can get a cat back system, dual tip or single shot, both will give you a lot more sound. when the shop you are looking at will do the cat back, they will most likely leave the stock main cat in place, and just put on new piping from there back, and a full 3" in sounds like a good size for a VR-4. Now, you can also go with redoing the front half also, like i first said with the downpipe+gutting the precats combo. this will also give you more sound out of your exhaust, but if you get rid of the main cat, it will be illegal and you will not pass emissions, what you can do is save the front half of you exahaust and just put it back on when you wanna go get emmissions testing done, or you can get a test pipe, which is basically a short pipe that goes in the exhaust system right where the main cat goes, so instead of switching out the whole front half of you exhaust you can just swap out the test pipe and put the main cat back in. Some places like 3sx sell a downpipe the replaces just the front pre-cat and ends right before the main cat, and you can just put on a test pipe to improve the airflow and sound.

So i think im just rambling now, but i hope i answered you questions, kinda. When you hear the phrase cat-back exhaust it just means the part behind the cat is being replaced, if you do both the front and the back, essentially the whole system, its called a turbo-back exhaust, that means that everything has been replaces, everything behind the turbos(precat-downpipe-main cat and then cat back from there). ok good luck with your decision

oh, and even if you decided to do the cat-back only, gutting the front and rear pre-cats is a good cheap(free if you already got tools) way to free up the air a bit and get a few extra HP.

*disclaimer* I am very far from being anything close to an expert so if I said anything that is incorrect or misleading, please tell me, I am only trying to help, not spread ignorance around. THANKS

[3000gt_vr4]

Originally Posted by axispiral

i had these same questions when i first starting thinking about doing exhaust, so I'm more than willing to help a fellow 3s'er out. ok

First, the things in red circles are the precats, they do the same thing as the main catalytic converter, but are mostly for when the car is starting from cold and the main cat is not heated up yet. Don't really need these, as Polygon stated earlier. Can gut them, like a lot of people on here do and still keep the pipe. the thing in the blue circle is the main catalytic converter, if you plan on passing emissions, keep this on, it is illegal to drive without one on you car. the whole part circled in the purple is what is going to be replaced if you buy an eBay downpipe. So make sure you know what youa re buying, and if its what you want. also, if you get a dp that replaces the main cat and front cat, all you have to do is gut the rear cat and you will have a VERY NICE SOUND. not too loud at idle and low rpms, but pretty mean at high revs. thats what I have right now and really like it. and in terms of HP gains, that is better than putting on a cat back. maybe later down the road if you are planning to make more power, you can up grade the whole system, but i've heard on here that the rest of the cat-back part of the exhaust doesn't restrict too much airflow untill you start making about 400hp crank (correct me if im wrong).

Now if you just want better sound, but not obnoxiously loud, the downpipe that replaces the main cat and front precat+gutting the rear precat would be good. and cheaper than a cat back system, but would make you car illegal, so you can do what you originally said and just get a cat back.

For the most part, it will not give you too much in the way of HP gains, but it will drastically change the sound of the car. The cat back is the part circled in the orange/brown color. That whole section of the exhaust system is located behind the catalytic converter and is thus called a cat-back (DUHH!!). This consists of some piping, the muffler/resonator, circled in green, and the exhaust tips. Now your car probably has active exhaust so that is what you see under the driver side of the car. The way exhaust works in our cars is that when in sport mode, the exhaust fumes come back into the main muffler, and it comes out of the two exhaust tips on the driver side as well as going through the pipe coming out of the main muffler and out to the tips on the passenger side as well. when in tour mode, it closes of the pipe going to the passenger side and makes the car quieter.

Now this is all cool to know, but if you're gonna change out the system, that all doesn't matter, just have the shop you go to fab a 1 to 2 split system, when the one pipe that comes back from the main cat splits into two pipes and you can put two separate mufflers on each of those. Thats seems to be what a lot of people on here do, put the mufflers right where the exhaust tips currently are. like this guy did

or if you are looking at performance and weight loss rather than just sound, you can look into a single shot exhaust, which basically just continues the single pipe coming back from the main cat, bends a few times and then has a muffler on it when it comes out the back of the car. This is "better" because it is less metal, which means less weight, and is an easier path for the air to escape out the back of the car, for example:


both will give you a lot more sound, but IMO the dual tip system just looks better, mostly because our cars came with duals and there are two spots on our bumpers.

Basically, there are a few things you can do to get more sound, as you said you wanted. you can get a cat back system, dual tip or single shot, both will give you a lot more sound. when the shop you are looking at will do the cat back, they will most likely leave the stock main cat in place, and just put on new piping from there back, and a full 3" in sounds like a good size for a VR-4. Now, you can also go with redoing the front half also, like i first said with the downpipe+gutting the precats combo. this will also give you more sound out of your exhaust, but if you get rid of the main cat, it will be illegal and you will not pass emissions, what you can do is save the front half of you exahaust and just put it back on when you wanna go get emmissions testing done, or you can get a test pipe, which is basically a short pipe that goes in the exhaust system right where the main cat goes, so instead of switching out the whole front half of you exhaust you can just swap out the test pipe and put the main cat back in. Some places like 3sx sell a downpipe the replaces just the front pre-cat and ends right before the main cat, and you can just put on a test pipe to improve the airflow and sound.

So i think im just rambling now, but i hope i answered you questions, kinda. When you hear the phrase cat-back exhaust it just means the part behind the cat is being replaced, if you do both the front and the back, essentially the whole system, its called a turbo-back exhaust, that means that everything has been replaces, everything behind the turbos(precat-downpipe-main cat and then cat back from there). ok good luck with your decision

oh, and even if you decided to do the cat-back only, gutting the front and rear pre-cats is a good cheap(free if you already got tools) way to free up the air a bit and get a few extra HP.

*disclaimer* I am very far from being anything close to an expert so if I said anything that is incorrect or misleading, please tell me, I am only trying to help, not spread ignorance around. THANKS

OK This is perfect you know how to help people out, pictures and everything.

ok i kinda wsa planning on doing the cat back and gutting the precats first, then getting a down pipe that keeps all cat.

but i had a ?? is there any down pipes with out any cats or will it be better to just cut them out and just have pipe with bung holes for the sensors.

and somthing that i berly learned to day that came to my intrest, that active exhaust, i kinda want to keep it. and just set new pipe around the active muffler. if any one has any pics or infor on where the active exhaust begins and ends that would be great,\


thanks so much for this info.

[kywhitelightning]

3SX sells one for $400 I believe. It eliminates all cats pre and main.